The present invention relates to a valve. More particularly, the present invention relates to a fluidic or air valve defining at least a first flow path with a modulating device such as a disk or flapper and a second, unmodulated flow path.
One method of suppressing fire and explosions in an aircraft fuel tank is to provide a non-explosive atmosphere within the fuel tank by replacing potentially combustible air in a fuel tank ullage (i.e., the space within the fuel tank unoccupied by fuel) with an inerting gas, such as nitrogen-enriched air (NEA). An onboard inerting system is often used to supply NEA (or another inerting gas) into the tank ullage when the demand arises (e.g., in order to increase the pressure inside the ullage in response to changing atmospheric conditions or to otherwise maintain the oxygen content in the ullage at or below a desirable level). The inerting system can typically include a nitrogen generating system (NGS) that separates nitrogen from high pressure air generated by a single compressor, or series of compressors within the system. Ram air (i.e., air from outside the aircraft), independent of the high pressure air circuit, is the heat sink source to cool the hot compressed air generated by the compressors. Both ram air and compressor air flows thru a heat exchanger to exchange heat.
In one type of NGS, ram air is fed to the NGS through a single inlet duct. A component's modulating valve controls flow of ram air to the NGS, such as a plurality of heat exchangers. The NGS output level typically depends on the amount of inert air required to fill the fuel tank ullage to maintain an inert environment. The modulating valve helps to achieve various NGS nitrogen gas output levels by controlling the amount of ram air that is directed to the heat exchangers to cool the heat of compressed air from the compressors. The amount of heat transfer is dependent upon flow thru the compressors to accommodate the NGS desired output.
It has been found that in at least one particular NGS, a dedicated constant flow of ram air is desirable for multiple purposes, such as cooling a compressor motor and/or because at least one of the plurality of heat exchangers requires a constant flow of air. Given the space constraints in many aircraft, it may be undesirable to modify the NGS system to include more than one inlet duct to provide for modulating and constant ram flows to the heat exchanger. As a result, both the constant flow and modulated flow of ram air must be provided through a single inlet duct leading to the valve. There is a need for a valve design that provides multiple out flows, including at least one constant out flow, without requiring substantial modification of current NGS inlet duct dimensions.